In this blog, young surgeons preparing for the MRCS part I exam will find totally free, syllabus-based, single best answer questions in applied basic science arranged by topic. New MCQsare added at least twice weekly. So keep in touch.

27 Mar 2009

MRCS: Anatomy MCQs 1

Abdomen, pelvis and perineum

1. All the following structures lie in the transpyloric plane EXCEPT:

a) origin of the inferior mesenteric arteryb) fundus of the gall-bladderc) termination of the spinal cordd) pancreatic necke) duodenojejunal flexure

2. Which of the following is true concerning the abdominal planes?

a) The transpyloric plane of Addison lies half-way between the xiphoid and the pubisb) The subcostal plane lies at the level of L1 vertebrac) The hila of the kidneys lie in the transpyloric planed) The intertubercular plane lies at the level of the pubic tuberclese) The level of the subcostal plane is a little higher than that of the transpyloric plane.

3. The superficial perineal fascia (of Colles)

a) is a continuation into the perineum of Camper's fasciab) encloses the superficial perineal spacec) is attached to the anterior margin of the perineal membrane.d) limits the extravasation of urine to the tissues of scrotum and penis in cases of rupture of the penile urethrae) allows extravasation of urine into the thigh in cases of rupture of the penile urethra.

4. Regarding the segmental innervation of the abdominal muscles and the overlying skin, all the following is true EXCEPT

a) it is derived from T7 to L1b) the umbilicus is supplied by T1c) the groin and scrotum are supplied by L1d) The abdominal reflexes are absent in lower motor neuron lesions.e) T7 innervates the skin over the xiphoid process

5. Which of the following statements about the oesophagus is true?

a) It begins at the level of C6 vertebrab) It begins at the upper border of the cricoid cartilagec) It passes through the diaphragm at the level of T10 vertebrad) It is about 35 cm longe) The intra-adbominal part averages 3-5 cm

6. Concerning the anal canal, which of the following statements is INCORRECT?

a) The upper end of the anal canal is supplied by the superior rectal artery.b) The upper canal drains to the superficial inguinal lymph nodes.c) The area below the pectinate line is supplied by the inferior rectal branches of the pudendal nerve.d) The upper canal and the lower canal differ in their embryological origin.e) The upper canal is a site of portal-systemic anastomosis.

7. The suprarenal glands:

a) are symmetrical in shapeb) Each gland receives blood only from its corresponding adrenal artery.c) Each gland is usually drained by a single vein.d) The inferior vena cava is an anterior relation of the left suprarenal gland.e) Both the cortex and medulla are supplied by parasympathetic nerves.

8. All the following statements concerning the kidneys are true EXCEPT:

a) They are retroperitoneal organs.b) Their lower poles may be palpated in the normal individualc) The right kidney lies in a higher position than the left.d) The kidneys move vertically with respiration.e) The perinephric fascia (of Gerota) surrounds the perinephric fat.

9. Concerning the relations of the kidneys:

a) On the left, the hilum is related to the second part of the duodenum.b) On the right, the hilum is related to the tail of the pancreasc) The costodiaphragmatic recess of the pleura is at risk in the lumbar approach to the kidney.d) The hilum of both kidneys lies at the subcostal plane.e) The kidney and suprarenal gland lie in the same fascial compartment.

10. Which of the following statements concerning the three main structures of the hilum of the kidney is INCORRECT?

a) The renal pelvis is normally the most posterior of the threeb) The anatomy of the contents of the hilum can be variable.c) The renal artery divides into 3-5 segmental arteries at the hilum.d) The right renal vein is longer than the left.e) The renal veins empty directly into the inferior vena cava.

Answers

1. a.

The origin of the inferior mesenteric artery lies in the subcostal plane.

2. c.

The transpyloric plane lies half-way between the suprasternal notch and the pubis, or approximately a hand’s breadth below the xiphoid. The subcostal plane lies at the level of L3 (a little lower than the transpyloric plane which passes at the lower border of L1). The intertubercular plane lies at the level of the tubercles of the iliac crest.

3. b.

The superficial perineal fascia (of Colles) is a continuation into the perineum of the membranous fascia (of Scarpa) from the anterior abdominal wall. It is attached to the ischiopubic rami and the posterior margin of the perineal membrane, thus closing in a subfascial space, the superficial perineal space (pouch), that is in continuity with the space deep to the membranous fascia of the anterior abdominal wall. Rupture of the penile urethra permits extravasation of urine beneath Colles' fascia whence the collection distends the tissues of the scrotum and penis and can then pass upwards over the anterior abdominal wall beneath Scarpa's fascia. Conversely, urine does not track into the thigh because of the attachment of Scarpa's fascia to the deep fascia of the thigh.

4. d.

The abdominal reflex is elicited by lightly stroking across each quadrant of the anterior abdominal wall. Normally there is contraction of the underlying muscles, but the reflexes are absent in upper motor neuron lesions.

5. a.

The oesophagus begins at the lower border of the cricoid cartilage at the level of C6 vertebra. It passes through the diaphragm at the level of T10 vertebra. It is about 25 cm (10 inches) long. The intra-abdominal part of the oesophagus varies in length according to the tone of its muscle and the degree of distension of the stomach. It averages 1-2 cm.

6. b.

The upper part of the anal canal (above the pectinate line) is endodermal, and the lower part is derived from the ectoderm.The following important anatomical facts with clinical significance result from this derivation of the anal canal:· - The upper half of the canal is lined by columnar epithelium and the lower half with stratified squamous epithelium, thus a carcinoma of the upper canal is an adenocarcinoma, while that arising from the lower part would be a squamous cell carcinoma).· - The upper half of the canal is supplied by the autonomic nervous system; the lower part has somatic innervation from the inferior rectal branches of the pudendal nerve. The lower part of the canal, therefore, is sensitive to pinprick sensation, while the upper part is not. This is an important factor when injecting haemorrhoids, where the needle should be inserted through the upper, insensitive part of the anal canal.· - The upper half of the canal drains into the portal venous system, whereas the lower drains into the systemic venous system. The two systems communicate and, therefore, this forms one site of anastomosis between the portal and the systemic circulations and may result in dilatated veins in portal hypertension.· - The lymphatic drainage of the upper half of the canal is along the superior rectal vessels to the abdominal nodes, whereas, below this site, drainage is to the inguinal nodes. This is clinically important, as a carcinoma of the rectum which grows down into the lower anal canal may metastasize to the inguinal nodes.

The superior rectal artery supplies the whole of the rectum and the upper half of the anal canal, while the inferior rectal supplies the lower half of the anal canal. The middle rectal artery is small and supplies only the muscle coats of the rectum.

7. c.The suprarenal glands lie anterosuperior to the upper pole of each kidney and are asymmetrical (The right gland is pyramidal and the left is crescentic in shape). The anterior surface of the right suprarenal gland is overlapped medially by the IVC. The glands have a rich blood supply; each receives blood from 3 sources which are (from superior to inferior) the inferior phrenic artery, the adrenal artery (directly from the aorta) and the renal artery. In contrast there is usually a single vein. Sympathetic nerves supply the cortex and the medulla.

8. c.The kidneys lie high up on the posterior abdominal wall behind the peritoneum, largely under cover of the costal margin. At best only the lower poles can be palpated in the normal individual. The hilum of the right kidney lies just below, and of the left kidney just above, the transpyloric plane 5 cm from the midline. The bulk of the right lobe of the liver accounts for the lower position of the right kidney. Each kidney moves in a vertical range of 2-2.5 cm during the full respiratory excursion of the diaphragm. The kidney and the perinephric fat are surrounded by the perinephric (Gerota's) fascia which separates the kidney from the suprarenal glands.

9.c.The hilum of both kidneys lies roughly at the level of L1 (the transpyloric plane). On the right the hilum is related to the second part of the duodenum and on the left to the tail of the pancreas. A small triangular part of the costodiaphragmatic recess of the pleura lies behind the diaphragm and is an important posterior relation, which is at risk in the lumbar approach to the kidney. The adrenal glands lie within a separate compartment of the renal fascia.

10.d.The renal vein, renal artery and renal pelvis enter and leave the kidney at the level of the hilum and are situated anatomically in relation to each other in the order mentioned above, moving in an anteroposterior direction. The anatomy of the contents of the hilum can be variable (e.g. The renal pelvis can be bifid, and the renal artery and vein may split into branches or receive tributaries, respectively, to a variable extent at the hilum). This can lead to confusion at the time of surgical dissection in this area. The renal artery divides into 3-5 segmental arteries at the hilum, which divide within the sinus into 6-10 interlobular veins – one for each pyramid and associated cortex. The renal veins follow the arterial pattern closely. The renal veins empty directly into the IVC. Since the IVC lies on the right side of the abdomen, the left renal vein is longer than the right.